A businessman, who had sex with a 15-year-old at a massage centre he operated, was on Tuesday jailed for 1 1/2 years for sexual penetration of a minor.

Ong Huat Kok, 50, met the girl in 2003 when she was 9. Her parents took her to his centre for a massage because she had a chronic ache in her left shoulder. She continued going for the massage at least once a month.

In September 2010, Ong asked the teen, who was then 15, to have sex with him. He was married to a Chinese national but he told the teen that he was single. He asked the girl, who was also single, if he could be her "part-time boyfriend". She agreed.

He then had unprotected sex with her at the shop, Li Kang Therapy Centre, at Hougang Avenue 3. He told her to leave by the back door and not tell anyone about the incident. He repeated this on two other occasions. In sentencing him, District Judge Eddy Tham noted the wide disparity in their ages, and said that the wider the age gap, the more culpable the culprit, who is expected to exercise greater control as a mature adult. He also considered Ong's previous sexual offences. Ong was sentenced to 28 months in jail and nine strokes of the cane in 1997 for outraging the modesty of a woman.